Night lights for residential use for providing a dim illumination for corridors and the like are well known in the art. Generally, these lights are of two types: first, a low wattage bulb is energized directly from the voltage available at the electrical outlet. Second, a normal wattage light bulb for conventional illumination is utilized in conjunction with a series connected resistance or capacitor to effect dimming of the bulb and thus provide a desired dim illumination.
In the first of the above types, the normal 110-volts available at the electrial outlet is applied across the bulb. The wattage of the bulb is small to provide the desired dim illumination and towards this end, the current through the bulb is quite limited. Excess energy results in the generation of heat by the relatively high resistance of the filament. While these types of night lights serve their purpose, they suffer the disadvantage of all electrically operated light bulbs when energized directly from an electrical wall outlet in that, in addition to heat generation, the bulbs must be periodically replaced since their useful life is limited.
The second type of night lights wherein a capacitor or resistance is utilized in series with a conventional bulb provides certain advantages. First, the voltage across the bulb itself is substantially less than normal voltage rating of the bulb with the desired result of extremely long life. On the other hand, if a resistance is used in series with the bulb to provide the reduced voltage, heat is generated in the resistance and such can be an undesirable feature since heat itself over long periods of time tends to accelerate the deterioration of the housing and insulation on the wires. Where a capacitance is used to drop the voltage, the night light can run cool and also exhibits the advantage of extremely long life. On the other hand, should the capacitor short circuit or fail, the bulb itself will be illuminated to its fullest brightness and this result could be undesirable since again substantial heat will be generated and the life of the bulb will be substantially shortened. Further, depending upon the type of capacitor and failure therein, a relatively high current will be passing through the defective structure to energize the bulb and this could result in a fire hazard or other possible damage.